This invention relates generally to methods and apparatus for servicing refrigeration systems and more particularly concerns the recovery of refrigerants from such systems without release of refrigerant to the atmosphere.
Predecessors to the present refrigerant recovery system are disclosed in my earlier U.S. Pat. No. 5,320,224 and patent application Ser. No. 134,045, soon to be issued as a patent. While the previous systems perform quite well in that the series arrangement of vacuum pump and compressor facilitates achievement of a deep vacuum in the disabled unit, a cryogenic type of pressure regulator was required to protect the vacuum pump. As a result, while otherwise unachievable vacuum levels for this kind of equipment were obtained, the operation of the system was slowed considerably.
In addition, in switching earlier refrigerant recovery systems from liquid to vapor evacuation, three-way valves requiring manual operation were employed. In some applications, when the operator failed to switch the valve from liquid to vapor flow before starting the compressor, the result was severe damage to the compressor.
Moreover, none of the earlier systems, regardless of their efficiency, permitted evacuation of the repaired disabled unit to the atmosphere through the same vacuum pump that had been used to evacuate the unit for repair. This lack further increased complexity of and time on the job.
At the same time, solutions to these problems give rise to a variety of difficulties in devising a refrigerant recovery unit useable to recover both liquid refrigerant and gaseous refrigerant from a disabled unit, to evacuate a refrigerant receiving can and to evacuate the repaired disabled unit and the recovery unit to a deep vacuum.
It is, therefore, an object of this invention to provide a refrigerant recovery unit capable of performing the evacuation of liquid and gaseous refrigerant from the disabled unit as well as the evacuation of receiving cans and of the refrigerant recovery unit itself. It is also an object of this invention to provide a refrigerant recovery unit capable of performing this multitude of functions with the gaseous refrigerant evacuation process proceeding at faster rates than in earlier systems. It is another object of this invention to provide a refrigerant recovery system which automatically transfers from the liquid recovery to the gaseous recovery flow conditions when the condenser is switched on. And it is an object of this invention to provide a refrigerant recovery unit which permits evacuation of a repaired refrigeration unit to the atmosphere using the same vacuum pump used during the refrigerant evacuation process prior to repair.